这部分暂时不重要，先pass，有时间了，把Github的整理学下.

If you are unfamiliar with GitHub , Udacity has a brief GitHub tutorial to get you started. Udacity also provides a more detailed free course on git and GitHub. To learn about REAMDE files and Markdown, Udacity provides a free course on READMEs, as well. GitHub also provides a tutorial about creating Markdown files.